HK Open-top bus tour

Which open top bus operator is better?
The Big Bus or the brand new "Rickshaw Sightseeing tour"?
It seems that the Rickshaw has more coverages, but it is so new... but also so economy ($50 One Day Pass vs $320 Big Bus)
Any one have tried them before?
http://www.bigbustours.com/eng/hongkong/
http://www.rickshawbus.com.hk